OAuth Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track J. Bradley
Expires: November 1, 2014 Ping Identity
N. Sakimura
NRI
April 30, 2014
JSON Web Token (JWT)draft-ietf-oauth-json-web-token-20
Abstract
JSON Web Token (JWT) is a compact URL-safe means of representing
claims to be transferred between two parties. The claims in a JWT
are encoded as a JavaScript Object Notation (JSON) object that is
used as the payload of a JSON Web Signature (JWS) structure or as the
plaintext of a JSON Web Encryption (JWE) structure, enabling the
claims to be digitally signed or MACed and/or encrypted.
The suggested pronunciation of JWT is the same as the English word
"jot".
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 1, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Internet-Draft JSON Web Token (JWT) April 20141. Introduction
JSON Web Token (JWT) is a compact claims representation format
intended for space constrained environments such as HTTP
Authorization headers and URI query parameters. JWTs encode claims
to be transmitted as a JavaScript Object Notation (JSON) [RFC7159]
object that is used as the payload of a JSON Web Signature (JWS)
[JWS] structure or as the plaintext of a JSON Web Encryption (JWE)
[JWE] structure, enabling the claims to be digitally signed or MACed
and/or encrypted. JWTs are always represented using the JWS Compact
Serialization or the JWE Compact Serialization.
The suggested pronunciation of JWT is the same as the English word
"jot".
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in Key
words for use in RFCs to Indicate Requirement Levels [RFC2119]. If
these words are used without being spelled in uppercase then they are
to be interpreted with their normal natural language meanings.
2. Terminology
JSON Web Token (JWT)
A string representing a set of claims as a JSON object that is
encoded in a JWS or JWE, enabling the claims to be digitally
signed or MACed and/or encrypted.
Base64url Encoding
Base64 encoding using the URL- and filename-safe character set
defined in Section 5 of RFC 4648 [RFC4648], with all trailing '='
characters omitted (as permitted by Section 3.2) and without the
inclusion of any line breaks, white space, or other additional
characters. (See Appendix C of [JWS] for notes on implementing
base64url encoding without padding.)
JWT Header
A JSON object that describes the cryptographic operations applied
to the JWT. When the JWT is digitally signed or MACed, the JWT
Header is a JWS Header. When the JWT is encrypted, the JWT Header
is a JWE Header.
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Header Parameter
A name/value pair that is member of the JWT Header.
Header Parameter Name
The name of a member of the JWT Header.
Header Parameter Value
The value of a member of the JWT Header.
JWT Claims Set
A JSON object that contains the Claims conveyed by the JWT.
Claim
A piece of information asserted about a subject. A Claim is
represented as a name/value pair consisting of a Claim Name and a
Claim Value.
Claim Name
The name portion of a Claim representation. A Claim Name is
always a string.
Claim Value
The value portion of a Claim representation. A Claim Value can be
any JSON value.
Encoded JWT Header
Base64url encoding of the JWT Header.
Nested JWT
A JWT in which nested signing and/or encryption are employed. In
nested JWTs, a JWT is used as the payload or plaintext value of an
enclosing JWS or JWE structure, respectively.
Plaintext JWT
A JWT whose Claims are not integrity protected or encrypted.
Collision-Resistant Name
A name in a namespace that enables names to be allocated in a
manner such that they are highly unlikely to collide with other
names. Examples of collision-resistant namespaces include: Domain
Names, Object Identifiers (OIDs) as defined in the ITU-T X.660 and
X.670 Recommendation series, and Universally Unique IDentifiers
(UUIDs) [RFC4122]. When using an administratively delegated
namespace, the definer of a name needs to take reasonable
precautions to ensure they are in control of the portion of the
namespace they use to define the name.
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StringOrURI
A JSON string value, with the additional requirement that while
arbitrary string values MAY be used, any value containing a ":"
character MUST be a URI [RFC3986]. StringOrURI values are
compared as case-sensitive strings with no transformations or
canonicalizations applied.
IntDate
A JSON numeric value representing the number of seconds from 1970-
01-01T0:0:0Z UTC until the specified UTC date/time. See RFC 3339
[RFC3339] for details regarding date/times in general and UTC in
particular.
3. JSON Web Token (JWT) Overview
JWTs represent a set of claims as a JSON object that is encoded in a
JWS and/or JWE structure. This JSON object is the JWT Claims Set. As
per Section 4 of [RFC7159], the JSON object consists of zero or more
name/value pairs (or members), where the names are strings and the
values are arbitrary JSON values. These members are the claims
represented by the JWT.
The member names within the JWT Claims Set are referred to as Claim
Names. The corresponding values are referred to as Claim Values.
The contents of the JWT Header describe the cryptographic operations
applied to the JWT Claims Set. If the JWT Header is a JWS Header, the
JWT is represented as a JWS, and the claims are digitally signed or
MACed, with the JWT Claims Set being the JWS Payload. If the JWT
Header is a JWE Header, the JWT is represented as a JWE, and the
claims are encrypted, with the JWT Claims Set being the input
Plaintext. A JWT may be enclosed in another JWE or JWS structure to
create a Nested JWT, enabling nested signing and encryption to be
performed.
A JWT is represented as a sequence of URL-safe parts separated by
period ('.') characters. Each part contains a base64url encoded
value. The number of parts in the JWT is dependent upon the
representation of the resulting JWS or JWE object using the JWS
Compact Serialization or the JWE Compact Serialization.
3.1. Example JWT
The following example JWT Header declares that the encoded object is
a JSON Web Token (JWT) and the JWT is a JWS that is MACed using the
HMAC SHA-256 algorithm:
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{"typ":"JWT",
"alg":"HS256"}
To remove potential ambiguities in the representation of the JSON
object above, the octet sequence for the actual UTF-8 representation
used in this example for the JWT Header/JWS Header above is also
included below. (Note that ambiguities can arise due to differing
platform representations of line breaks (CRLF versus LF), differing
spacing at the beginning and ends of lines, whether the last line has
a terminating line break or not, and other causes. In the
representation used in this example, the first line has no leading or
trailing spaces, a CRLF line break (13, 10) occurs between the first
and second lines, the second line has one leading space (32) and no
trailing spaces, and the last line does not have a terminating line
break.) The octets representing the UTF-8 representation of the JWS
Header in this example (using JSON array notation) are:
[123, 34, 116, 121, 112, 34, 58, 34, 74, 87, 84, 34, 44, 13, 10, 32,
34, 97, 108, 103, 34, 58, 34, 72, 83, 50, 53, 54, 34, 125]
Base64url encoding the octets of the UTF-8 representation of the JWT
Header yields this Encoded JWT Header value (which is also the
underlying encoded JWS Header value):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
The following is an example of a JWT Claims Set:
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
The following octet sequence, which is the UTF-8 representation used
in this example for the JWT Claims Set above, is the JWS Payload:
[123, 34, 105, 115, 115, 34, 58, 34, 106, 111, 101, 34, 44, 13, 10,
32, 34, 101, 120, 112, 34, 58, 49, 51, 48, 48, 56, 49, 57, 51, 56,
48, 44, 13, 10, 32, 34, 104, 116, 116, 112, 58, 47, 47, 101, 120, 97,
109, 112, 108, 101, 46, 99, 111, 109, 47, 105, 115, 95, 114, 111,
111, 116, 34, 58, 116, 114, 117, 101, 125]
Base64url encoding the JWS Payload yields this encoded JWS Payload
(with line breaks for display purposes only):
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly
9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ
Computing the MAC of the encoded JWS Header and encoded JWS Payload
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with the HMAC SHA-256 algorithm and base64url encoding the HMAC value
in the manner specified in [JWS], yields this encoded JWS Signature:
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
Concatenating these encoded parts in this order with period ('.')
characters between the parts yields this complete JWT (with line
breaks for display purposes only):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
This computation is illustrated in more detail in Appendix A.1 of
[JWS]. See Appendix A.1 for an example of an encrypted JWT.
4. JWT Claims
The JWT Claims Set represents a JSON object whose members are the
claims conveyed by the JWT. The Claim Names within a JWT Claims Set
MUST be unique; recipients MUST either reject JWTs with duplicate
Claim Names or use a JSON parser that returns only the lexically last
duplicate member name, as specified in Section 15.12 (The JSON
Object) of ECMAScript 5.1 [ECMAScript].
The set of claims that a JWT must contain to be considered valid is
context-dependent and is outside the scope of this specification.
Specific applications of JWTs will require implementations to
understand and process some claims in particular ways. However, in
the absence of such requirements, all claims that are not understood
by implementations MUST be ignored.
There are three classes of JWT Claim Names: Registered Claim Names,
Public Claim Names, and Private Claim Names.
4.1. Registered Claim Names
The following Claim Names are registered in the IANA JSON Web Token
Claims registry defined in Section 10.1. None of the claims defined
below are intended to be mandatory to use or implement in all cases,
but rather, provide a starting point for a set of useful,
interoperable claims. Applications using JWTs should define which
specific claims they use and when they are required or optional. All
the names are short because a core goal of JWTs is for the
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representation to be compact.
4.1.1. "iss" (Issuer) Claim
The "iss" (issuer) claim identifies the principal that issued the
JWT. The processing of this claim is generally application specific.
The "iss" value is a case-sensitive string containing a StringOrURI
value. Use of this claim is OPTIONAL.
4.1.2. "sub" (Subject) Claim
The "sub" (subject) claim identifies the principal that is the
subject of the JWT. The Claims in a JWT are normally statements
about the subject. The subject value MAY be scoped to be locally
unique in the context of the issuer or MAY be globally unique. The
processing of this claim is generally application specific. The
"sub" value is a case-sensitive string containing a StringOrURI
value. Use of this claim is OPTIONAL.
4.1.3. "aud" (Audience) Claim
The "aud" (audience) claim identifies the recipients that the JWT is
intended for. Each principal intended to process the JWT MUST
identify itself with a value in the audience claim. If the principal
processing the claim does not identify itself with a value in the
"aud" claim when this claim is present, then the JWT MUST be
rejected. In the general case, the "aud" value is an array of case-
sensitive strings, each containing a StringOrURI value. In the
special case when the JWT has one audience, the "aud" value MAY be a
single case-sensitive string containing a StringOrURI value. The
interpretation of audience values is generally application specific.
Use of this claim is OPTIONAL.
4.1.4. "exp" (Expiration Time) Claim
The "exp" (expiration time) claim identifies the expiration time on
or after which the JWT MUST NOT be accepted for processing. The
processing of the "exp" claim requires that the current date/time
MUST be before the expiration date/time listed in the "exp" claim.
Implementers MAY provide for some small leeway, usually no more than
a few minutes, to account for clock skew. Its value MUST be a number
containing an IntDate value. Use of this claim is OPTIONAL.
4.1.5. "nbf" (Not Before) Claim
The "nbf" (not before) claim identifies the time before which the JWT
MUST NOT be accepted for processing. The processing of the "nbf"
claim requires that the current date/time MUST be after or equal to
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the not-before date/time listed in the "nbf" claim. Implementers MAY
provide for some small leeway, usually no more than a few minutes, to
account for clock skew. Its value MUST be a number containing an
IntDate value. Use of this claim is OPTIONAL.
4.1.6. "iat" (Issued At) Claim
The "iat" (issued at) claim identifies the time at which the JWT was
issued. This claim can be used to determine the age of the JWT. Its
value MUST be a number containing an IntDate value. Use of this
claim is OPTIONAL.
4.1.7. "jti" (JWT ID) Claim
The "jti" (JWT ID) claim provides a unique identifier for the JWT.
The identifier value MUST be assigned in a manner that ensures that
there is a negligible probability that the same value will be
accidentally assigned to a different data object. The "jti" claim
can be used to prevent the JWT from being replayed. The "jti" value
is a case-sensitive string. Use of this claim is OPTIONAL.
4.2. Public Claim Names
Claim Names can be defined at will by those using JWTs. However, in
order to prevent collisions, any new Claim Name should either be
registered in the IANA JSON Web Token Claims registry defined in
Section 10.1 or be a Public Name: a value that contains a Collision-
Resistant Name. In each case, the definer of the name or value needs
to take reasonable precautions to make sure they are in control of
the part of the namespace they use to define the Claim Name.
4.3. Private Claim Names
A producer and consumer of a JWT MAY agree to use Claim Names that
are Private Names: names that are not Registered Claim Names
Section 4.1 or Public Claim Names Section 4.2. Unlike Public Claim
Names, Private Claim Names are subject to collision and should be
used with caution.
5. JWT Header
The members of the JSON object represented by the JWT Header describe
the cryptographic operations applied to the JWT and optionally,
additional properties of the JWT. The member names within the JWT
Header are referred to as Header Parameter Names. These names MUST
be unique; recipients MUST either reject JWTs with duplicate Header
Parameter Names or use a JSON parser that returns only the lexically
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last duplicate member name, as specified in Section 15.12 (The JSON
Object) of ECMAScript 5.1 [ECMAScript]. The corresponding values are
referred to as Header Parameter Values.
JWS Header Parameters are defined by [JWS]. JWE Header Parameters
are defined by [JWE]. This specification further specifies the use
of the following Header Parameters in both the cases where the JWT is
a JWS and where it is a JWE.
5.1. "typ" (Type) Header Parameter
The "typ" (type) Header Parameter defined by [JWS] and [JWE] is used
to declare the MIME Media Type [IANA.MediaTypes] of this complete JWT
in contexts where this is useful to the application. This parameter
has no effect upon the JWT processing. If present, it is RECOMMENDED
that its value be "JWT" to indicate that this object is a JWT. While
media type names are not case-sensitive, it is RECOMMENDED that "JWT"
always be spelled using uppercase characters for compatibility with
legacy implementations. Use of this Header Parameter is OPTIONAL.
5.2. "cty" (Content Type) Header Parameter
The "cty" (content type) Header Parameter defined by [JWS] and [JWE]
is used by this specification to convey structural information about
the JWT.
In the normal case where nested signing or encryption operations are
not employed, the use of this Header Parameter is NOT RECOMMENDED.
In the case that nested signing or encryption is employed, this
Header Parameter MUST be present; in this case, the value MUST be
"JWT", to indicate that a Nested JWT is carried in this JWT. While
media type names are not case-sensitive, it is RECOMMENDED that "JWT"
always be spelled using uppercase characters for compatibility with
legacy implementations. See Appendix A.2 for an example of a Nested
JWT.
5.3. Replicating Claims as Header Parameters
In some applications using encrypted JWTs, it is useful to have an
unencrypted representation of some Claims. This might be used, for
instance, in application processing rules to determine whether and
how to process the JWT before it is decrypted.
This specification allows Claims present in the JWT Claims Set to be
replicated as Header Parameters in a JWT that is a JWE, as needed by
the application. If such replicated Claims are present, the
application receiving them SHOULD verify that their values are
identical, unless the application defines other specific processing
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rules for these Claims. It is the responsibility of the application
to ensure that only claims that are safe to be transmitted in an
unencrypted manner are replicated as Header Parameter Values in the
JWT.
Section 10.4.1 of this specification registers the "iss" (issuer),
"sub" (subject), and "aud" (audience) Header Parameter Names for the
purpose of providing unencrypted replicas of these Claims in
encrypted JWTs for applications that need them. Other specifications
MAY similarly register other names that are registered Claim Names as
Header Parameter Names, as needed.
6. Plaintext JWTs
To support use cases where the JWT content is secured by a means
other than a signature and/or encryption contained within the JWT
(such as a signature on a data structure containing the JWT), JWTs
MAY also be created without a signature or encryption. A plaintext
JWT is a JWS using the "none" JWS "alg" Header Parameter Value
defined in JSON Web Algorithms (JWA) [JWA]; it is a JWS with the
empty string for its JWS Signature value.
6.1. Example Plaintext JWT
The following example JWT Header declares that the encoded object is
a Plaintext JWT:
{"alg":"none"}
Base64url encoding the octets of the UTF-8 representation of the JWT
Header yields this Encoded JWT Header:
eyJhbGciOiJub25lIn0
The following is an example of a JWT Claims Set:
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
Base64url encoding the octets of the UTF-8 representation of the JWT
Claims Set yields this encoded JWS Payload (with line breaks for
display purposes only):
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
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The encoded JWS Signature is the empty string.
Concatenating these encoded parts in this order with period ('.')
characters between the parts yields this complete JWT (with line
breaks for display purposes only):
eyJhbGciOiJub25lIn0
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
7. Rules for Creating and Validating a JWT
To create a JWT, the following steps MUST be taken. The order of the
steps is not significant in cases where there are no dependencies
between the inputs and outputs of the steps.
1. Create a JWT Claims Set containing the desired claims. Note that
white space is explicitly allowed in the representation and no
canonicalization need be performed before encoding.
2. Let the Message be the octets of the UTF-8 representation of the
JWT Claims Set.
3. Create a JWT Header containing the desired set of Header
Parameters. The JWT MUST conform to either the [JWS] or [JWE]
specifications. Note that white space is explicitly allowed in
the representation and no canonicalization need be performed
before encoding.
4. Depending upon whether the JWT is a JWS or JWE, there are two
cases:
* If the JWT is a JWS, create a JWS using the JWT Header as the
JWS Header and the Message as the JWS Payload; all steps
specified in [JWS] for creating a JWS MUST be followed.
* Else, if the JWT is a JWE, create a JWE using the JWT Header
as the JWE Header and the Message as the JWE Plaintext; all
steps specified in [JWE] for creating a JWE MUST be followed.
5. If a nested signing or encryption operation will be performed,
let the Message be the JWS or JWE, and return to Step 3, using a
"cty" (content type) value of "JWT" in the new JWT Header created
in that step.
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6. Otherwise, let the resulting JWT be the JWS or JWE.
When validating a JWT, the following steps MUST be taken. The order
of the steps is not significant in cases where there are no
dependencies between the inputs and outputs of the steps. If any of
the listed steps fails then the JWT MUST be rejected for processing.
1. The JWT MUST contain at least one period ('.') character.
2. Let the Encoded JWT Header be the portion of the JWT before the
first period ('.') character.
3. The Encoded JWT Header MUST be successfully base64url decoded
following the restriction given in this specification that no
padding characters have been used.
4. The resulting JWT Header MUST be completely valid JSON syntax
conforming to [RFC7159].
5. The resulting JWT Header MUST be validated to only include
parameters and values whose syntax and semantics are both
understood and supported or that are specified as being ignored
when not understood.
6. Determine whether the JWT is a JWS or a JWE using any of the
methods described in Section 9 of [JWE].
7. Depending upon whether the JWT is a JWS or JWE, there are two
cases:
* If the JWT is a JWS, all steps specified in [JWS] for
validating a JWS MUST be followed. Let the Message be the
result of base64url decoding the JWS Payload.
* Else, if the JWT is a JWE, all steps specified in [JWE] for
validating a JWE MUST be followed. Let the Message be the
JWE Plaintext.
8. If the JWT Header contains a "cty" (content type) value of
"JWT", then the Message is a JWT that was the subject of nested
signing or encryption operations. In this case, return to Step
1, using the Message as the JWT.
9. Otherwise, let the JWT Claims Set be the Message.
10. The JWT Claims Set MUST be completely valid JSON syntax
conforming to [RFC7159].
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Internet-Draft JSON Web Token (JWT) April 20147.1. String Comparison Rules
Processing a JWT inevitably requires comparing known strings to
values in JSON objects. For example, in checking what the algorithm
is, the Unicode string encoding "alg" will be checked against the
member names in the JWT Header to see if there is a matching Header
Parameter Name.
Comparisons between JSON strings and other Unicode strings MUST be
performed by comparing Unicode code points without normalization, as
specified in the String Comparison Rules in Section 5.3 of [JWS].
8. Implementation Requirements
This section defines which algorithms and features of this
specification are mandatory to implement. Applications using this
specification can impose additional requirements upon implementations
that they use. For instance, an application might require support
for encrypted JWTs and Nested JWTs; another might require support for
signing JWTs with ECDSA using the P-256 curve and the SHA-256 hash
algorithm ("ES256").
Of the signature and MAC algorithms specified in JSON Web Algorithms
(JWA) [JWA], only HMAC SHA-256 ("HS256") and "none" MUST be
implemented by conforming JWT implementations. It is RECOMMENDED
that implementations also support RSASSA-PKCS1-V1_5 with the SHA-256
hash algorithm ("RS256") and ECDSA using the P-256 curve and the SHA-
256 hash algorithm ("ES256"). Support for other algorithms and key
sizes is OPTIONAL.
Support for encrypted JWTs is OPTIONAL. If an implementation
provides encryption capabilities, of the encryption algorithms
specified in [JWA], only RSAES-PKCS1-V1_5 with 2048 bit keys
("RSA1_5"), AES Key Wrap with 128 and 256 bit keys ("A128KW" and
"A256KW"), and the composite authenticated encryption algorithm using
AES CBC and HMAC SHA-2 ("A128CBC-HS256" and "A256CBC-HS512") MUST be
implemented by conforming implementations. It is RECOMMENDED that
implementations also support using ECDH-ES to agree upon a key used
to wrap the Content Encryption Key ("ECDH-ES+A128KW" and
"ECDH-ES+A256KW") and AES in Galois/Counter Mode (GCM) with 128 bit
and 256 bit keys ("A128GCM" and "A256GCM"). Support for other
algorithms and key sizes is OPTIONAL.
Support for Nested JWTs is OPTIONAL.
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Internet-Draft JSON Web Token (JWT) April 20149. URI for Declaring that Content is a JWT
This specification registers the URN
"urn:ietf:params:oauth:token-type:jwt" for use by applications that
declare content types using URIs (rather than, for instance, MIME
Media Types) to indicate that the content referred to is a JWT.
10. IANA Considerations10.1. JSON Web Token Claims Registry
This specification establishes the IANA JSON Web Token Claims
registry for JWT Claim Names. The registry records the Claim Name
and a reference to the specification that defines it. This
specification registers the Claim Names defined in Section 4.1.
Values are registered with a Specification Required [RFC5226] after a
two-week review period on the [TBD]@ietf.org mailing list, on the
advice of one or more Designated Experts. However, to allow for the
allocation of values prior to publication, the Designated Expert(s)
may approve registration once they are satisfied that such a
specification will be published.
Registration requests must be sent to the [TBD]@ietf.org mailing list
for review and comment, with an appropriate subject (e.g., "Request
for access token type: example"). [[ Note to the RFC Editor: The name
of the mailing list should be determined in consultation with the
IESG and IANA. Suggested name: jwt-reg-review. ]]
Within the review period, the Designated Expert(s) will either
approve or deny the registration request, communicating this decision
to the review list and IANA. Denials should include an explanation
and, if applicable, suggestions as to how to make the request
successful. Registration requests that are undetermined for a period
longer than 21 days can be brought to the IESG's attention (using the
iesg@iesg.org mailing list) for resolution.
Criteria that should be applied by the Designated Expert(s) includes
determining whether the proposed registration duplicates existing
functionality, determining whether it is likely to be of general
applicability or whether it is useful only for a single application,
and whether the registration makes sense.
IANA must only accept registry updates from the Designated Expert(s)
and should direct all requests for registration to the review mailing
list.
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It is suggested that multiple Designated Experts be appointed who are
able to represent the perspectives of different applications using
this specification, in order to enable broadly-informed review of
registration decisions. In cases where a registration decision could
be perceived as creating a conflict of interest for a particular
Expert, that Expert should defer to the judgment of the other
Expert(s).
10.1.1. Registration Template
Claim Name:
The name requested (e.g., "example"). Because a core goal of this
specification is for the resulting representations to be compact,
it is RECOMMENDED that the name be short -- not to exceed 8
characters without a compelling reason to do so. This name is
case-sensitive. Names may not match other registered names in a
case-insensitive manner unless the Designated Expert(s) state that
there is a compelling reason to allow an exception in this
particular case.
Claim Description:
Brief description of the Claim (e.g., "Example description").
Change Controller:
For Standards Track RFCs, state "IESG". For others, give the name
of the responsible party. Other details (e.g., postal address,
email address, home page URI) may also be included.
Specification Document(s):
Reference to the document(s) that specify the parameter,
preferably including URI(s) that can be used to retrieve copies of
the document(s). An indication of the relevant sections may also
be included but is not required.
10.1.2. Initial Registry Contents
o Claim Name: "iss"
o Claim Description: Issuer
o Change Controller: IESG
o Specification Document(s): Section 4.1.1 of [[ this document ]]
o Claim Name: "sub"
o Claim Description: Subject
o Change Controller: IESG
o Specification Document(s): Section 4.1.2 of [[ this document ]]
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o Change Controller: IESG
o Specification Document(s): Section 4.1.3 of [[ this document ]]
11. Security Considerations
All of the security issues faced by any cryptographic application
must be faced by a JWT/JWS/JWE/JWK agent. Among these issues are
protecting the user's private and symmetric keys, preventing various
attacks, and helping the user avoid mistakes such as inadvertently
encrypting a message for the wrong recipient. The entire list of
security considerations is beyond the scope of this document.
All the security considerations in the JWS specification also apply
to JWT, as do the JWE security considerations when encryption is
employed. In particular, the JWS JSON Security Considerations and
Unicode Comparison Security Considerations apply equally to the JWT
Claims Set in the same manner that they do to the JWS Header.
While syntactically, the signing and encryption operations for Nested
JWTs may be applied in any order, normally senders should sign the
message and then encrypt the result (thus encrypting the signature).
This prevents attacks in which the signature is stripped, leaving
just an encrypted message, as well as providing privacy for the
signer. Furthermore, signatures over encrypted text are not
considered valid in many jurisdictions.
Note that potential concerns about security issues related to the
order of signing and encryption operations are already addressed by
the underlying JWS and JWE specifications; in particular, because JWE
only supports the use of authenticated encryption algorithms,
cryptographic concerns about the potential need to sign after
encryption that apply in many contexts do not apply to this
specification.
The contents of a JWT cannot be relied upon in a trust decision
unless its contents have been cryptographically secured and bound to
the context necessary for the trust decision. In particular, the
key(s) used to sign and/or encrypt the JWT will typically need to
verifiably be under the control of the party identified as the issuer
of the JWT.
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Internet-Draft JSON Web Token (JWT) April 2014Section 6.1 and Appendices A.1, A.2, and A.3 of [JWS].
A.1. Example Encrypted JWT
This example encrypts the same claims as used in Section 3.1 to the
recipient using RSAES-PKCS1-V1_5 and AES_128_CBC_HMAC_SHA_256.
The following example JWE Header (with line breaks for display
purposes only) declares that:
o the Content Encryption Key is encrypted to the recipient using the
RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and
o the Plaintext is encrypted using the AES_128_CBC_HMAC_SHA_256
algorithm to produce the Ciphertext.
{"alg":"RSA1_5","enc":"A128CBC-HS256"}
Other than using the octets of the UTF-8 representation of the JWT
Claims Set from Section 3.1 as the plaintext value, the computation
of this JWT is identical to the computation of the JWE in AppendixA.2 of [JWE], including the keys used.
The final result in this example (with line breaks for display
purposes only) is:
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.
QR1Owv2ug2WyPBnbQrRARTeEk9kDO2w8qDcjiHnSJflSdv1iNqhWXaKH4MqAkQtM
oNfABIPJaZm0HaA415sv3aeuBWnD8J-Ui7Ah6cWafs3ZwwFKDFUUsWHSK-IPKxLG
TkND09XyjORj_CHAgOPJ-Sd8ONQRnJvWn_hXV1BNMHzUjPyYwEsRhDhzjAD26ima
sOTsgruobpYGoQcXUwFDn7moXPRfDE8-NoQX7N7ZYMmpUDkR-Cx9obNGwJQ3nM52
YCitxoQVPzjbl7WBuB7AohdBoZOdZ24WlN1lVIeh8v1K4krB8xgKvRU8kgFrEn_a
1rZgN5TiysnmzTROF869lQ.
AxY8DCtDaGlsbGljb3RoZQ.
MKOle7UQrG6nSxTLX6Mqwt0orbHvAKeWnDYvpIAeZ72deHxz3roJDXQyhxx0wKaM
HDjUEOKIwrtkHthpqEanSBNYHZgmNOV7sln1Eu9g3J8.
fiK51VwhsxJ-siBMR-YFiA
A.2. Example Nested JWT
This example shows how a JWT can be used as the payload of a JWE or
JWS to create a Nested JWT. In this case, the JWT Claims Set is
first signed, and then encrypted.
The inner signed JWT is identical to the example in Appendix A.2 of
[JWS]. Therefore, its computation is not repeated here. This
example then encrypts this inner JWT to the recipient using RSAES-
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PKCS1-V1_5 and AES_128_CBC_HMAC_SHA_256.
The following example JWE Header (with line breaks for display
purposes only) declares that:
o the Content Encryption Key is encrypted to the recipient using the
RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key,
o the Plaintext is encrypted using the AES_128_CBC_HMAC_SHA_256
algorithm to produce the Ciphertext, and
o the Plaintext is itself a JWT.
{"alg":"RSA1_5","enc":"A128CBC-HS256","cty":"JWT"}
Base64url encoding the octets of the UTF-8 representation of the JWE
Header yields this encoded JWE Header value:
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiY3R5IjoiSldUIn0
The computation of this JWT is identical to the computation of the
JWE in Appendix A.2 of [JWE], other than that different JWE Header,
Plaintext, Initialization Vector, and Content Encryption Key values
are used. (The RSA key used is the same.)
The Payload used is the octets of the ASCII representation of the JWT
at the end of Appendix A.2.1 of [JWS] (with all whitespace and line
breaks removed), which is a sequence of 458 octets.
The Initialization Vector value used (using JSON array notation) is:
[82, 101, 100, 109, 111, 110, 100, 32, 87, 65, 32, 57, 56, 48, 53,
50]
This example uses the Content Encryption Key represented in JSON Web
Key [JWK] format below:
{"kty":"oct",
"k":"GawgguFyGrWKav7AX4VKUg"
}
The final result for this Nested JWT (with line breaks for display
purposes only) is:
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eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiY3R5IjoiSldU
In0.
g_hEwksO1Ax8Qn7HoN-BVeBoa8FXe0kpyk_XdcSmxvcM5_P296JXXtoHISr_DD_M
qewaQSH4dZOQHoUgKLeFly-9RI11TG-_Ge1bZFazBPwKC5lJ6OLANLMd0QSL4fYE
b9ERe-epKYE3xb2jfY1AltHqBO-PM6j23Guj2yDKnFv6WO72tteVzm_2n17SBFvh
DuR9a2nHTE67pe0XGBUS_TK7ecA-iVq5COeVdJR4U4VZGGlxRGPLRHvolVLEHx6D
YyLpw30Ay9R6d68YCLi9FYTq3hIXPK_-dmPlOUlKvPr1GgJzRoeC9G5qCvdcHWsq
JGTO_z3Wfo5zsqwkxruxwA.
UmVkbW9uZCBXQSA5ODA1Mg.
VwHERHPvCNcHHpTjkoigx3_ExK0Qc71RMEParpatm0X_qpg-w8kozSjfNIPPXiTB
BLXR65CIPkFqz4l1Ae9w_uowKiwyi9acgVztAi-pSL8GQSXnaamh9kX1mdh3M_TT
-FZGQFQsFhu0Z72gJKGdfGE-OE7hS1zuBD5oEUfk0Dmb0VzWEzpxxiSSBbBAzP10
l56pPfAtrjEYw-7ygeMkwBl6Z_mLS6w6xUgKlvW6ULmkV-uLC4FUiyKECK4e3WZY
Kw1bpgIqGYsw2v_grHjszJZ-_I5uM-9RA8ycX9KqPRp9gc6pXmoU_-27ATs9XCvr
ZXUtK2902AUzqpeEUJYjWWxSNsS-r1TJ1I-FMJ4XyAiGrfmo9hQPcNBYxPz3GQb2
8Y5CLSQfNgKSGt0A4isp1hBUXBHAndgtcslt7ZoQJaKe_nNJgNliWtWpJ_ebuOpE
l8jdhehdccnRMIwAmU1n7SPkmhIl1HlSOpvcvDfhUN5wuqU955vOBvfkBOh5A11U
zBuo2WlgZ6hYi9-e3w29bR0C2-pp3jbqxEDw3iWaf2dc5b-LnR0FEYXvI_tYk5rd
_J9N0mg0tQ6RbpxNEMNoA9QWk5lgdPvbh9BaO195abQ.
AVO9iT5AV4CzvDJCdhSFlQ
Appendix B. Relationship of JWTs to SAML Assertions
SAML 2.0 [OASIS.saml-core-2.0-os] provides a standard for creating
security tokens with greater expressivity and more security options
than supported by JWTs. However, the cost of this flexibility and
expressiveness is both size and complexity. SAML's use of XML
[W3C.CR-xml11-20021015] and XML DSIG [RFC3275] contributes to the
size of SAML assertions; its use of XML and especially XML
Canonicalization [W3C.REC-xml-c14n-20010315] contributes to their
complexity.
JWTs are intended to provide a simple security token format that is
small enough to fit into HTTP headers and query arguments in URIs.
It does this by supporting a much simpler token model than SAML and
using the JSON [RFC7159] object encoding syntax. It also supports
securing tokens using Message Authentication Codes (MACs) and digital
signatures using a smaller (and less flexible) format than XML DSIG.
Therefore, while JWTs can do some of the things SAML assertions do,
JWTs are not intended as a full replacement for SAML assertions, but
rather as a token format to be used when ease of implementation or
compactness are considerations.
SAML Assertions are always statements made by an entity about a
subject. JWTs are often used in the same manner, with the entity
making the statements being represented by the "iss" (issuer) claim,
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and the subject being represented by the "sub" (subject) claim.
However, with these claims being optional, other uses of the JWT
format are also permitted.
Appendix C. Relationship of JWTs to Simple Web Tokens (SWTs)
Both JWTs and Simple Web Tokens SWT [SWT], at their core, enable sets
of claims to be communicated between applications. For SWTs, both
the claim names and claim values are strings. For JWTs, while claim
names are strings, claim values can be any JSON type. Both token
types offer cryptographic protection of their content: SWTs with HMAC
SHA-256 and JWTs with a choice of algorithms, including signature,
MAC, and encryption algorithms.
Appendix D. Acknowledgements
The authors acknowledge that the design of JWTs was intentionally
influenced by the design and simplicity of Simple Web Tokens [SWT]
and ideas for JSON tokens that Dick Hardt discussed within the OpenID
community.
Solutions for signing JSON content were previously explored by Magic
Signatures [MagicSignatures], JSON Simple Sign [JSS], and Canvas
Applications [CanvasApp], all of which influenced this draft.
This specification is the work of the OAuth Working Group, which
includes dozens of active and dedicated participants. In particular,
the following individuals contributed ideas, feedback, and wording
that influenced this specification:
Dirk Balfanz, Richard Barnes, Brian Campbell, Breno de Medeiros, Dick
Hardt, Joe Hildebrand, Jeff Hodges, Edmund Jay, Yaron Y. Goland, Ben
Laurie, James Manger, Prateek Mishra, Tony Nadalin, Axel Nennker,
John Panzer, Emmanuel Raviart, David Recordon, Eric Rescorla, Jim
Schaad, Paul Tarjan, Hannes Tschofenig, and Sean Turner.
Hannes Tschofenig and Derek Atkins chaired the OAuth working group
and Sean Turner, Stephen Farrell, and Kathleen Moriarty served as
Security area directors during the creation of this specification.
Appendix E. Document History
[[ to be removed by the RFC Editor before publication as an RFC ]]
-20
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o Changed the RFC 6755 reference to be normative.
o Changed the JWK reference to be informative.
o Described potential sources of ambiguity in representing the JSON
objects used in the examples. The octets of the actual UTF-8
representations of the JSON objects used in the examples are
included to remove these ambiguities.
o Noted that octet sequences are depicted using JSON array notation.
-19
o Specified that support for Nested JWTs is optional and that
applications using this specification can impose additional
requirements upon implementations that they use.
o Updated the JSON reference to RFC 7159.
-18
o Clarified that the base64url encoding includes no line breaks,
white space, or other additional characters.
o Removed circularity in the audience claim definition.
o Clarified that it is entirely up to applications which claims to
use.
o Changed "SHOULD" to "MUST" in "in the absence of such
requirements, all claims that are not understood by
implementations MUST be ignored".
o Clarified that applications can define their own processing rules
for claims replicated in header parameters, rather than always
requiring that they be identical in the JWT Header and JWT Claims
Set.
o Removed a JWT creation step that duplicated a step in the
underlying JWS or JWE creation.
o Added security considerations about using JWTs in trust decisions.
-17
o Corrected RFC 2119 terminology usage.
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o Replaced references to draft-ietf-json-rfc4627bis with RFC 7158.
-16
o Changed some references from being normative to informative, per
JOSE issue #90.
-15
o Replaced references to RFC 4627 with draft-ietf-json-rfc4627bis.
-14
o Referenced the JWE section on Distinguishing between JWS and JWE
Objects.
-13
o Added Claim Description registry field.
o Used Header Parameter Description registry field.
o Removed the phrases "JWA signing algorithms" and "JWA encryption
algorithms".
o Removed the term JSON Text Object.
-12
o Tracked the JOSE change refining the "typ" and "cty" definitions
to always be MIME Media Types, with the omission of "application/"
prefixes recommended for brevity. For compatibility with legacy
implementations, it is RECOMMENDED that "JWT" always be spelled
using uppercase characters when used as a "typ" or "cty" value.
As side effects, this change removed the "typ" Claim definition
and narrowed the uses of the URI
"urn:ietf:params:oauth:token-type:jwt".
o Updated base64url definition to match JOSE definition.
o Changed terminology from "Reserved Claim Name" to "Registered
Claim Name" to match JOSE terminology change.
o Applied other editorial changes to track parallel JOSE changes.
o Clarified that the subject value may be scoped to be locally
unique in the context of the issuer or may be globally unique.
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-11
o Added a Nested JWT example.
o Added "sub" to the list of Claims registered for use as Header
Parameter values when an unencrypted representation is required in
an encrypted JWT.
-10
o Allowed Claims to be replicated as Header Parameters in encrypted
JWTs as needed by applications that require an unencrypted
representation of specific Claims.
-09
o Clarified that the "typ" header parameter is used in an
application-specific manner and has no effect upon the JWT
processing.
o Stated that recipients MUST either reject JWTs with duplicate
Header Parameter Names or with duplicate Claim Names or use a JSON
parser that returns only the lexically last duplicate member name.
-08
o Tracked a change to how JWEs are computed (which only affected the
example encrypted JWT value).
-07
o Defined that the default action for claims that are not understood
is to ignore them unless otherwise specified by applications.
o Changed from using the term "byte" to "octet" when referring to 8
bit values.
o Tracked encryption computation changes in the JWE specification.
-06
o Changed the name of the "prn" claim to "sub" (subject) both to
more closely align with SAML name usage and to use a more
intuitive name.
o Allow JWTs to have multiple audiences.
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o Applied editorial improvements suggested by Jeff Hodges, Prateek
Mishra, and Hannes Tschofenig. Many of these simplified the
terminology used.
o Explained why Nested JWTs should be signed and then encrypted.
o Clarified statements of the form "This claim is OPTIONAL" to "Use
of this claim is OPTIONAL".
o Referenced String Comparison Rules in JWS.
o Added seriesInfo information to Internet Draft references.
-05
o Updated values for example AES CBC calculations.
-04
o Promoted Initialization Vector from being a header parameter to
being a top-level JWE element. This saves approximately 16 bytes
in the compact serialization, which is a significant savings for
some use cases. Promoting the Initialization Vector out of the
header also avoids repeating this shared value in the JSON
serialization.
o Applied changes made by the RFC Editor to RFC 6749's registry
language to this specification.
o Reference RFC 6755 -- An IETF URN Sub-Namespace for OAuth.
-03
o Added statement that "StringOrURI values are compared as case-
sensitive strings with no transformations or canonicalizations
applied".
o Indented artwork elements to better distinguish them from the body
text.
-02
o Added an example of an encrypted JWT.
o Added this language to Registration Templates: "This name is case
sensitive. Names that match other registered names in a case
insensitive manner SHOULD NOT be accepted."
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